1. Field of the Invention
The present invention relates to a technology of adjusting and generating synchronization signals.
2. Description of the Related Art
Recently, it has become common for households to build a storage system in which a network attached storage (NAS) is connected to a computer network. An NAS is a file server provided with a hard disk drive and is configured to provide a content file to a client device via a TCP/IP network.
Some NASs are provided with a tuner compatible with terrestrial digital broadcast and satellite digital broadcast. Users can view a live program or view a recorded program at a client device via the TCP/IP network. In this process, program data are converted into a data format such as Moving Picture Experts Group (MPEG) 2 Transport Stream (TS) and delivered accordingly.
To view a live program delivered in a live stream primarily using an NAS via a TCP/IP network, a certain amount of data is buffered before the data is transmitted or played back, for the purpose of canceling variation in the bit rate of the streaming data. When the data is temporarily buffered in an NAS, etc. before being transmitted to a client device, the timing of arrival at the client device is shifted from the timing of transmission at a broadcast station. Therefore, the timing of synchronizing an image and sound transmitted by a broadcast station need be reproduced in order to view a live program delivered in a stream via a TCP/IP network.
Normally, an oscillator for generating a timing signal in a broadcast station and an oscillator used for synchronization in a client device are different and are considered to contain a slight error. The error will be normegligible if the program is viewed for a long period of time. A technology is called for capable of correcting the error.